Athermal evolution of nanocrystalline tungsten driven by irradiation

PW Ma and DR Mason and S Van Boxel and SL Dudarev, JOURNAL OF NUCLEAR MATERIALS, 586, 154662 (2023).

DOI: 10.1016/j.jnucmat.2023.154662

Radiation effects in nanocrystalline tungsten are simulated in the athermal high dose limit, where microstructural evolution is driven not by the thermally activated diffusion of radiation defects, but by the fluctuating stress field resulting from the production and relaxation of defects. Over a large interval of exposure spanning several dpa, samples with smaller grains swell less than those with larger grains, featuring defect denuded zones resulting from the continuously fluctuating atomic configurations at grain boundaries. The grain size distribution broadens as a function of exposure, with the average grain size increasing, subject to the visibility criterion applied to the identification of small grains. This work makes a quantitative analysis of how the dynamic recombination of defects in the grain boundary region, responsible for the known superior radiation resistance of nanocrystalline materials, emerges spontaneously in atomistic simulations.

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